Zero return for electromechanical integrators



Dec. 25, 195] 5, FAGlN 2,579,731

ZERO RETURN FOR ELECTROMECHANICAL INTEGRATORS Filed 00"). 20, 1949 INVENTOR SAMUEL L. FAG/N BY Jam m a# Fla/2% ATTORNEYS Patented Dec. 25, 1951 ZERO RETURN FOR ELECTROMECHANICAL INTEGRATORS Samuel L. Fagin, New York, N. Y., assignor to Engineering & Research Corporation, Riverdale, Md., a corporation of Maryland Application October 20, 1949, Serial No. 122,485

1 Claim. 1

This invention relates broadly to electromechanical integrators of the type which operates to displace an output shaft from a zero position by an amount which is a function of the integral of an input voltage. It has been found that in the use and operation of such integrators it is very diflicult and time-consuming to return the output shaft to zero position after the completion of a problem, and no means other than manual have heretofore been known to effect this return operation.

It is therefore the object and result of this invention to provide means for returning the output shaft of an electromechanical integrator to zero position after completion of a problem and in order to apply the integrator to a new problem.

An electromechanical integrator embodying the zero-return means accordin to my invention is disclosed in the single figure of the drawings. The integrator disclosed in this figure comprises a source of alternating or direct current 2 connected through switch 4, resistance 6 and amplitier 8 to a motor 10, the armature of which is connected through shaft II to a generator l2. Voltage generated by generator I2 is supplied through resistance 14 to the connection between resistor E and the input side of amplifier 8. The shaft H is connected through reduction gearing Hi to an output shaft IS, the displacement of which from a zero position is proportional to the integral of the input voltage supplied by source 2.

The foregoing apparatus comprises a conventional electromechanical integrator which operates in the following manner. An input voltage which is to be integrated, and which may be alternating current or direct current, is supplied to resistance 6 and is added algebraically to voltage from generator it by means of the resistors 5 and M. The amplification of the amplifier is so great as to keep the motor and generator running at a speed such that the voltage output of the generator very closely cancels the input signal voltage. The displacement of the potentiometer shaft to from zero position will therefore be a measure of the integration of the input voltage, all in accordance with known practice.

By this invention I provide means. for returning the output or potentiometer shaft l8 to zero position after it has been displaced therefrom in the integration of an input voltage. Such means comprise a potentiometer 26 the contact arm 2 of which is driven by the output shaft I 8 over the potentiometer resistance 24. The opposite end terminals of the resistance are connected to two sources of voltage which are of opposite polarity, if D. C., or of opposite phase if A. C., the center point 26 of the resistance accordingly being at zero potential. The contact arm 22 is connected through switch 28, resistance to and amplifler 8 to the motor [0 and the generator I2 is connected through resistance [4 to the connection between resistance 3!] and the amplifier, whereby voltage at the contact arm 22 due to its displacement from the zero potential point of potentiometer resistance 20 is added algebraically to voltage from generator 12 by means of the resistors 38 and M.

In the operation of an integrator embodying my invention it will be assumed that the operation of the integrator has caused displacement of the potentiometer shaft and contact arm clockwise from the zero potential point of resistance 24, as shown in the drawing. During this integration, switch 4 was closed and switch 28 was open. If it is now desired to return the potentiometer shaft to zero position the switch 4 is opened and switch 28 is closed. Voltage at the contact arm due to its displacement from the zero potential point of resistance 24 will now be supplied to resistor 30 and will be added algebraically to voltage generated by generator l2 and appearing across resistor 14. The motor will accordingly be rotated in such a direction as to return the output shaft 18 of the integrator and the movable contact 30 of the potentiometer to zero position where it will remain until the integrator is again operated.

While I have described and illustrated one embodiment of my invention, it will be apparent to those skilled in the art that other embodiments, as well as modifications thereof, may be made without departing in any way from the spirit or scope of the invention for the limits of which reference must be had to the appended claim.

What is claimed is:

In an electromechanical integrator of the type in which a shaft is displaced proportionally to the time integral of an incoming voltage, a motor, a shaft connected to said motor, a generator connected to said shaft, means connecting the output voltage of said generator to said motor, a first potential source, means normally connecting said first potential source to said motor for integration, means for returning said shaft to zero position comprising a second potential source, a potentiometer connected to said sec ond potential source whereby a zero potential point is established on said potentiometer, a contact arm on said potentiometer connected to said shaft, means for connecting said contact 3 arm to said motor and means for disconnecting UNITED STATES PATENTS said first potential source from said motor where- Number Name Date by the potential at the contact arm is combined 1 653 736 Shackleton Dec. 27 1927 with the voltage output of the generator to con- 2488448 Townes Nov 1949 trol said motor to return said shaft to zero po- 5 n sition and said contact arm to said zero poten- FOREIGN PATENTS tial Point Number I Countr a y Date SAMUEL FAGIN- 342,354 Great Britain Feb. 2, 1931 REFERENCES CITED 10 OTHER REFERENCES The following references are of record in the Electric Time Measurements, 1st ed., McGrawfil Of t s p t Hill Book Co., 1949, page 306 in particular. 

